29 January, 2014

There's been a lot of anticipation for our new off road touring bike, the Camargue. The frame prototypes have been very well received at shows, but there has been one comment that keeps coming up: why 26" wheels? The smaller sizes of the Camargue (47cm, 50cm, and 53cm) are all designed around 26" wheels. This is a big deal for some people because there is a common notion that 26" wheels are 'slow'. I think that in many ways this notion is misinformed. While it is true that wider tires cause more rolling resistance, the Camargue is designed for the same tire width across all frame sizes. In an ideal scenario, where tire and rim availability are not a factor, there should be two main factors in choosing wheel size: frame size, and intended riding type, with frame size being the most constraining factor.

Before we delve into this any more, some quick background. There are currently three wheel sizes prevalent on the market: 26" (559 BSD); 650b/27 1/2"(584 BSD); and 700c/29" (622 BSD). The 650b sizing has most recently had a resurgence in the mountain bike industry. The world of 650b wheels is no stranger to us at Velo Orange. We've been selling a 650b frame, the Polyvalent, for many years, along with rims and fenders. So why are there so many different wheel sizes? For a while most mountain bikers were riding 26" wheels, then everyone threw those away for 29" wheels, and now we're on to 27 1/2" wheels. The bicycle propaganda machine would have you believe that there are a bunch of scientists deliberating over the ideal wheel size. They're probably hard at work, running experiments in their labs, calculating inertia and rolling resistance and all of those things. In a few years we'll be one step closer to the true ideal wheel size (27"??), but for now we have 700c for road bikes and 27 1/2" for mountain bikes.

Here's why I think everyone keeps switching wheel sizes: planned obsolescence. Design for obsolescence (DFO) is a normal enough principle in the engineering world; it often goes hand in hand with design for failure (DFF). You can see plenty of examples of this in the phone and auto industries. However, the phone and auto industries have it a lot easier. They are selling more complicated products that the layman doesn't have the time to understand. They can make shoddy cars that will need to be replaced sooner than later. New technologies are often cited as reasons to convince the consumer to buy a new car. Fortunately, DFO isn't so easy in the bike industry. It's not hard to look at a bike and determine its overall quality. Likewise, it's not hard to make a bike that will last. This is a problem for the industry: the market has the potential to become saturated with frames, and frame sales will drop off to some degree. The solution to this problem is to convince everyone that their old frames are obsolete. Changing the predominant wheel size is a great way to do this.

Here is the good news: with the predominant wheel size constantly changing, there are more and more wheel and tire size options being made available. In my ideal world there would be tons of different wheel sizes, all with different rim width options and different tire type/size options. Like I said earlier, there should be two main design factors in choosing wheel size for a frame: type of riding and frame size. The frame size should be the dominant constraint. Ideally, wheel size should scale with frame size. When you design a frame around a wheel that is too large or too small for it you are forced to make sacrifices in the geometry which will affect handling. Proper handling should trump the supposed benefits of a certain wheel size. Thinking of a bicycle in terms of a tool, an extension of our bodies, it makes sense that it should be particularly sized to suit us. We buy a frame that fits us in the same way that we buy a pair of pants that fits us. Likewise, when you go to buy shoes you get a pair that fits you and is appropriate for how you intend to use them. A conniving salesmen might try to tell you that a larger size shoe would give you more traction because it has more surface area, and he'd be right, but you'd know that the blisters caused by too large of a shoe wouldn't be worth it.

For example, I'm 6'3" and Scott is 5'7". I ride a 59cm Camargue which has 29" wheels, and Scott rides the 53cm Camargue with 26" wheels.

Every now and then Scott hops on the 59cm Camargue prototype and rides it around the office. It looks quite silly -- no more so, however, than when he steals my boots and wears them around the office. (Scott is certainly an odd duck, but he's Canadian so we generally give him a pass.)

We're very excited about the new Camargue frames. We've put them through a lot of testing and are quite pleased with how they have performed. Early on, during the initial design stages of the Camargue, we had to decide between two competing metrics. On one hand we knew that people wanted 29" wheels, but we also wanted to design a frame that handled and fit the rider well. In the end, handling won out and this means that the smaller Camargue frames are designed around 26" wheels.

24 comments:

Except that's not true. I've measured in real-world conditions, and doubling the tire size and halving the pressure resulted in a faster commute to work (which surprised me, because I used to believe that skinny was faster) and a longer roll-out down a gentle hill. At high speeds wind resistance hurts big tires more, but that's not rolling resistance, and doesn't seem to matter enough at speeds below 12-ish mph (which is all I measured carefully).

Some details here, along with some links in the blog entry and in the comments.

And please, anyone who wishes to claim I'm wrong -- why do you think that? Did you measure performance, or are you relying on your subjective feel-o-meter? Did you just read it somewhere?

I tried to be intentional about how I worded that statement. I based it off of a study I read a while ago in undergrad, which I can't find right now, but if I find it I'll be sure to post it here. I don't by any means intend to claim that larger tires are slower. Rolling resistance is only one of many factors, relating to tires, which affects performance and speed.

I ride in Baltimore. With its prevalence of potholes, I'm much faster with larger tires.

On further reading, it looks like I should have been even more intentional with how I worded that statement. That statement is true in practice, because wider tires are run at a lower pressure. However, It is not true if you are comparing tires of different widths at the same pressure.

I'd like you guys to try out some Resist Nomad 2.25 tires on the Camargue to see what you think. They can take pretty high pressure, and although high volume high pressure may seem to defeat the purpose of the volume, it sure feels nice, at least on pavement.

I've brought up this notion of planned obsolescence a few times on The Retrogrouch Blog -- the numbers of people buying bicycles isn't growing enough to satisfy the big manufacturers -- so they have to keep finding ways to make existing customers think they need to either "upgrade" or add more bikes to their stables.

I'm glad to see bikes offered with different wheel sizes depending on frame size -- it makes a lot more sense than choosing wheel size based on industry fashion trends. Any time I see "29er" mountain bikes with little 19 - 20 inch frames, I cringe. The proportions of 29er MTBs tend to look pretty "tortured" anyhow -- but with smaller frames, it seems completely pointless -- no reason for it other than the fashion that 29er bikes are popular (or have they already peaked?).

About rolling resistance -- a lot of that has more to do with tire and casing construction more than wheel size. A 26" tire with a nice supple casing and a fine tread shouldn't roll appreciably differently than a similar tire on a 650b rim.

Arguments about tire rolling resistance almost universally fail to consider the riding surface. On smooth, hard pavement, these nice theoretical and laboratory measurements may mean something. As soon as you ride on soft or rough surfaces, things change. Narrow, high pressure tires cost you a lot more energy when they sink into a slightly soft surface or bump you unmercifully on a rough surface. I ride rails-to-trails a lot, and crushed stone is a common surface. In the spring, or after rain or after a new layer of stone has been laid down, it's always a bit soft. After a lot of riders have been on it when it was soft, and then it bakes in the sun, it's rough. When I switched from 35mm (actual) to 45mm (actual, 50 nominal) width tires, that I run at lower pressure. I found that I expended less energy on soft and rough surfaces, and I can't tell the difference on hard smooth surfaces. I won't be going back to 35mm tires, and I pity those who ride even narrower tires on these trails.

When I read that the Camargue would have 559 wheels on the smaller sizes and 622 on the larger, my thought was, "Finally!, another bike designer, besides Grant Petersen, is being sensible about wheel sizes!" It's a smart move. I hope you won't abandon it in the future.

I am a little confused concerning the sizing of the Camargue, Casey what is your PBH ? I have a height of 187 cm and a PBH of 87 cm. Comparing to the way my Surly LHT 60 cm was set up as well as the geometry charts, I believe I would have to get the Camargue in size 62 still you are higher than me and you ride a size 59 cm ??

Mark Holm, I think your point is central to the discussion about tire size. All things being equal (weight, pressure, casing, tread), two smooth tires of different sizes on a polished smooth surface will be similarly fast. However, on rough stuff, not only is a larger tire able to conform to the irregular surface, but the rider will feel more comfortable pushing the limits of the bike. While one can ride a lot of different surfaces on 35mm tires, that doesn't mean it is fast, efficient, safe, or fun. I choose wider tires for reasons that have nothing to do with roll-out testing.

Even as many of us claim to be "non-racers", I find it interesting that these discussions focus so heavily on speed and efficiency, with little attention given to safety and fun. Before we discredit the entire genre of mountain bikes, 29" wheels, and even suspension, it is worth noting that much of that corner of cycling is focused on fun. For me, that is immeasurably important. That which I have learned from mountain biking translates to all the bikes I ride, both on and off pavement.

Casey, thanks for this discussion. We are all looking forward to the Camargue.

Jan Heine in his magazine Bicycle Quarterly has done well-controlled tests, and found that wide, lower-pressure tires are indisputably not slower. Think about this: do race cars run skinny tires? Wider tires at reasonable pressure simply do not have higher rolling resistance. Jan has gone further to show that running at low pressure can even be faster, because of the road surface issues that Mark mentions. The science is in, fat tires are best for 90+% of the riding people do.

A hint to VO: You currently don't offer any tires that would be appropriate for the Camargue. I am running 622x50 Schwalbe Big Bens and am very pleased with them. On my rims, they actually measure about 45mm. the Big Ben is a nice, middle of the road, as it were, tire. It's not a slick, but it's not a knobby. It won't be tearing up grass or slinging mud, but it offers a bit of extra grip over a smooth tread. It runs well on pavement and on crushed stone and not too bad in mildly muddy or loose conditions.

I have a shorter torso, so I generally prefer to be on a slightly smaller frame relative to my height. Particularly so in the case of the Camargue, which effectively has square geometry on the 59cm frame(59cm effective top tube). Since the Camargue is intended for off road use I would suggest sizing down if you are between sizes.

@Mark Holm

We've been testing out big tires on the Camargue for a while. Once we get the Camargues in stock we'll start selling whichever tire that we like best.

I think it absolutely makes sense to design smaller frames around smaller wheel sizes, so kudos for that. One question I have is what is gained by going with a larger sized wheel for larger sized frames. Or what is better about using a 700c wheel with a 60cm frame vs. a 26" sized wheel?

I have to agree with the pro-wide tire commenters. I've commuted about 4600 miles on a pair of 26x2.35 Schwalbes I got in August of 2012.

I don't think there's a big rolling resistance penalty. When you go fast, there is a wind resistance penalty. Getting big tires up to speed or up a hill feels harder to me. But, as gypsybytrade mentioned the ride quality is spectacular!

To Soren Hansen: Please do not size a frame in relation to your PBH or to what the manufacturer sizes their frames. This is 100% incorrect. You can have 2 frame geometries completely different from one another but each have the manufacturer state or label the frame "size" the same cm. I've been fitting folks and been around bikes for a very long time, love me some Grant Peterson, but honestly, he knows absolutely nothing about how to size a frame proper. The most important factor in proper sizing is top tube length, followed by head tube length (as this will effect saddle to bar drop), with the seat tube length almost insignificant (you don't ride your bike straddling your top tube). The reason Grant gets away with this is because he builds many of his bikes with upright bars that sweep back. Take a look at images of his drop bar bikes. He has many with short stems or dirt drop stems to make up for the longer top tubes. That's not the correct way to set up a bike. And yes on Jan Heine. He does great research/studies on rolling resistance and is nuts on with his results. Even roadies are now running 25's on everything.

I've also come to discover that for myself, top tube length is the most important variable in sizing a bike. I can ride a bike with 77cm of S.O. and a bike with 84cm of S.O. with equal comfort and confidence but the bigger bike kills my lower back because the top-tube is extremely long.

The proportional top-tube is one thing that has me really excited about the Camargue. I probably would have already purchased an Ogre if not for it's ridiculously long top-tube.

Also, I wish the larger Camargues came with the option of 26" wheels. I find that the agility and quick acceleration of 26" wheels makes them more fun to ride than 700c wheels. Plus, big, plump fat tires just look more proportional on a 26" rim than they do on a 700c wheel.

I really look forward to the Camargue hitting the market. Not sure I'll be able to buy one but it's at the top of my list.

The crown for scaled frame sizing goes to Liteville bikes, the other company of Jo Klieber of Syntace fame, see here (not sure if links work on this blog but here goes):http://syntace.my1.cc/liteville/pdf/Scaled_Sizing_Flyer_neue_rahmen.pdfHe considers riders from 1,57m to 1,92m and recommends four! wheel sizes. These are MTBs btw.

My favorite bike ('72 Raleigh Grand Prix) came with 27" (630) wheels, and if that tire size were still as common and well-supported as 700c currently is, I would not have converted.The all-road bike we built last winter (old Raleigh SC30 comfort bike, drop bars, 26x1.95 tires)runs 26in/559 wheels because I want air volume to support my bulk, width for our farm roads, shorter spokes for wheel strength, and cheap, easily-obtainable hybrid-type tires. The wheels look small under me, but so would 630s.I think, ALL ELSE BEING EQUAL, wider tires have more rolling resistance, but loosing 40lbs would be a helluva lot more effective than suffering with 700x25 tires at 120psi. Or 559x38 tires at 85psi, which helped put me on the sag wagon in RAGBRAI. More air at lower psi is easier on me, the frame, and the spokes. If I lose that 40lbs, I'll keep the wider tires and lower the pressure.

When I go to the local bike shop and see a 5'3" woman test riding a Trekalized 29" mountain bike, I just laugh. The way the companies have to squeeze those huge wheels and tires on a small frame makes it look ridiculous and there is no way it can ride well. And the person test riding it is riding huge knobby tires in a parking lot.

That is what the companies try and sell because it is the current trend and meets the short-term goal of selling more bikes. The bike shops have to sell whatever Trekalized says or get cut off completely. It is in no one's best interest but the bike companies'. The long term goal of not pissing off your customers and keeping them for life does not seem to matter to them.